Drop-mold conformable material as an encapsulation for an integrated circuit package system

ABSTRACT

An integrated circuit package system includes: providing an integrated circuit; mounting a lead on the periphery of the integrated circuit; connecting the integrated circuit to the lead with an interconnect; and forming a conformable material by pressing the conformable material on the integrated circuit, the lead, and the interconnect.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/988,724 filed Nov. 16, 2007.

The present application contains subject matter related to co-pendingU.S. patent application Ser. No. 12/121,752. The related application isassigned to STATS ChipPAC Ltd.

The present application also contains subject matter related toco-pending U.S. patent application Ser. No. 12/126,684. The relatedapplication is assigned to STATS ChipPAC Ltd.

TECHNICAL FIELD

The present invention relates generally to integrated circuits and moreparticularly to a system for utilizing a drop-mold conformable materialas an encapsulation for an integrated circuit.

BACKGROUND ART

The rapidly growing portable electronics market, e.g. cellular phones,laptop computers, and PDAs, are an integral facet of modern life. Themultitude of portable devices represents one of the largest potentialmarket opportunities for next generation packaging. These devices haveunique attributes that have significant impacts on manufacturingintegration, in that they must be generally small, lightweight, and richin functionality and they must be produced in high volumes at relativelylow cost.

As an extension of the semiconductor industry, the electronics packagingindustry has witnessed ever-increasing commercial competitive pressures,along with growing consumer expectations and the diminishingopportunities for meaningful product differentiation in the marketplace.

Packaging, materials engineering, and development are at the very coreof these next generation electronics insertion strategies outlined inroad maps for development of next generation products. Future electronicsystems may be more intelligent, have higher density, use less power,operate at higher speed, and may include mixed technology devices andassembly structures at lower cost than today.

Current packaging suppliers are struggling to accommodate the high-speedcomputer devices that are projected to exceed one TeraHertz (THz) in thenear future. The current technologies, materials, equipment, andstructures offer challenges to the basic assembly of these new deviceswhile still not adequately addressing cooling and reliability concerns.

The envelope of technical capability of next level interconnectassemblies are not yet known, and no clear cost effective technology hasyet been identified. Beyond the performance requirements of nextgeneration devices, the industry now demands that cost be a primaryproduct differentiator in an attempt to meet profit goals.

As a result, the road maps are driving electronics packaging toprecision, ultra miniature form factors, which require automation inorder to achieve acceptable yield. These challenges demand not onlyautomation of manufacturing, but also the automation of data flow andinformation to the production manager and customer.

There have been many approaches to addressing the advanced packagingrequirements of microprocessors and portable electronics with successivegenerations of semiconductors. Many industry road maps have identifiedsignificant gaps between the current semiconductor capability and theavailable supporting electronic packaging technologies. The limitationsand issues with current technologies include increasing clock rates, EMIradiation, thermal loads, second level assembly reliability stresses andcost.

As these package systems evolve to incorporate more components withvaried environmental needs, the pressure to push the technologicalenvelope becomes increasingly challenging. More significantly, with theever-increasing complexity, the potential risk of error increasesgreatly during manufacture.

In view of the ever-increasing commercial competitive pressures, alongwith growing consumer expectations and the diminishing opportunities formeaningful product differentiation in the marketplace, it is criticalthat answers be found for these problems. Additionally, the need toreduce costs, reduce production time, improve efficiencies andperformance, and meet competitive pressures, adds an even greaterurgency to the critical necessity for finding answers to these problems.

Thus, a need remains for smaller footprints and more robust packages andmethods for manufacture. Solutions to these problems have been longsought but prior developments have not taught or suggested any solutionsand, thus, solutions to these problems have long eluded those skilled inthe art.

DISCLOSURE OF THE INVENTION

The present invention provides an integrated circuit package system thatincludes: providing an integrated circuit; mounting a lead on theperiphery of the integrated circuit; connecting the integrated circuitto the lead with an interconnect; and forming a conformable material bypressing the conformable material on the integrated circuit, the lead,and the interconnect.

Certain embodiments of the invention have other aspects in addition toor in place of those mentioned above. The aspects will become apparentto those skilled in the art from a reading of the following detaileddescription when taken with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom plan view of an integrated circuit package system ina first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the integrated circuit packagesystem taken along line 2-2 of FIG. 1;

FIG. 3 is the integrated circuit package system of FIG. 2 in a post leadproviding phase of manufacture;

FIG. 4 is the integrated circuit package system of FIG. 2 in awire-bonding phase of manufacture;

FIG. 5 is the integrated circuit package system of FIG. 2 in a dropconformable material-attaching phase of manufacture;

FIG. 6 is the integrated circuit package system of FIG. 2 in a curingphase of manufacture;

FIG. 7 is the integrated circuit package system of FIG. 2 in a postsingulation phase of manufacture;

FIG. 8 is a cross-sectional view along the line 8-8 of FIG. 1;

FIG. 9 is a cross-sectional view of an integrated circuit package systemin a second embodiment of the present invention;

FIG. 10 is a cross-sectional view of an integrated circuit packagesystem in a third embodiment of the present invention;

FIG. 11 is a cross-sectional view of an integrated circuit packagesystem in a fourth embodiment of the present invention;

FIG. 12 is a cross-sectional view of an integrated circuit packagesystem in a fifth embodiment of the present invention;

FIG. 13 is a cross-sectional view of an integrated circuit packagesystem in a sixth embodiment of the present invention;

FIG. 14 is a cross-sectional view of an integrated circuit packagesystem in a seventh embodiment of the present invention;

FIG. 15 is a cross-sectional view of an integrated circuit packagesystem in an eighth embodiment of the present invention;

FIG. 16 is a cross-sectional view of an integrated circuit packagesystem in a ninth embodiment of the present invention;

FIG. 17 is a cross-sectional view of an integrated circuit packagesystem in a tenth embodiment of the present invention; and

FIG. 18 is a flow chart of a system for manufacturing the integratedcircuit package system of FIG. 1 in an embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following embodiments are described in sufficient detail to enablethose skilled in the art to make and use the invention. It is to beunderstood that other embodiments would be evident based on the presentdisclosure, and that system, process, or mechanical changes may be madewithout departing from the scope of the present invention.

In the following description, numerous specific details are given toprovide a thorough understanding of the invention. However, it will beapparent that the invention may be practiced without these specificdetails. In order to avoid obscuring the present invention, somewell-known circuits, system configurations, and process steps are notdisclosed in detail.

Likewise, the drawings showing embodiments of the system aresemi-diagrammatic and not to scale and, particularly, some of thedimensions are for the clarity of presentation and are shown greatlyexaggerated in the drawing FIGs. The same numbers are used in all thedrawing FIGs. to relate to the same elements. The embodiments have beennumbered first embodiment, second embodiment, etc. as a matter ofdescriptive convenience and are not intended to have any othersignificance or provide limitations for the present invention.

For expository purposes, the term “horizontal” as used herein is definedas a plane parallel to the plane or surface of the integrated circuit,regardless of its orientation. The term “vertical” refers to a directionperpendicular to the horizontal as just defined. Terms, such as “above”,“below”, “bottom”, “top”, “side” (as in “sidewall”), “higher”, “lower”,“upper”, “over”, and “under”, are defined with respect to the horizontalplane. The term “on” means that there is direct contact among elements.

The term “processing” as used herein includes deposition of material orphotoresist, patterning, exposure, development, etching, cleaning,and/or removal of the material or photoresist as required in forming adescribed structure. The term “system” as used herein refers to and isdefined as the method and as the apparatus of the present invention inaccordance with the context in which the term is used.

Referring now to FIG. 1, therein is shown a bottom plan view of anintegrated circuit package system 100 in a first embodiment of thepresent invention. The integrated circuit package system 100 is shownhaving an integrated circuit 102.

On the periphery of the integrated circuit 102, are leads 104. Partiallyencapsulating the integrated circuit 102 and the leads 104 is aconformable material 106.

Referring now to FIG. 2, therein is shown a cross-sectional view of theintegrated circuit package system 100 taken along line 1-1 of FIG. 1.The integrated circuit package system 100 is shown with the integratedcircuit 102 such as a wire-bonded die having an active side 204.

On the periphery of the integrated circuit 102, the leads 104 are shownhaving an upper surface 208. The upper surface 208 of the leads 104 areconnected to the active side 204 of the integrated circuit 102 withinterconnects 210 such as bond wires.

The leads 104 are shown having a half-etched portion 212 below the uppersurface 208 of the leads 104. The leads 104 are further shown exposedalong a side 214 and a bottom 216, providing more area exposed forwetting during board level attachment and board level reliability can beimproved.

The leads 104 may be pre-plated with Ni, Pt, Au or any combination ofthem. The leads 104 also can be arranged in single or multiple rowformats to match multiple levels of stacked die.

Encapsulating the interconnects 210 and partially encapsulating theintegrated circuit 102 and the leads 104, is the conformable material106. The conformable material 106 has a low viscosity and, astemperature increases, the viscosity gets lower.

Therefore, the conformable material 106 can be easily pressed over theinterconnects 210, above, and around the integrated circuit 102 and theleads 104, and then cured to harden the conformable material 106.

The leads 104 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 106. The conformable material 106 is shown onlypartially encapsulating the half-etched portion 212 of the leads 104.

It has been discovered that the conformable material 106 should be athermally conductive dielectric material. The conformable material 106can be made of a B-stage material that can be hardened after curing.

The conformable material 106 should be about 100° C. while encapsulatingthe integrated circuit 102 before curing. The viscosity of theconformable material 106 may be in a range of 10 Pa to 2000 Pa. It hasstill further been discovered that the elastic modulus of theconformable material 106 before curing (B-stage) should be less than 300MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 106, a bufferlayer 220 is mounted.

The buffer layer 220 is used to compensate for the coefficient ofthermal expansion mismatch between the conformable material 106 and anadhesive layer 222 attached above the buffer layer 220. It is preferablethat the buffer layer 220 is made of an insulation material.

The adhesive layer 222 may be applied to secure a stiffener 224 abovethe buffer layer 220. The buffer layer 220, the adhesive layer 222, andthe stiffener 224 are preferably thermally conductive to shed excessheat generated by the operation of the integrated circuit 102.

The stiffener 224 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 106 in its uncured or viscous state.

When the stiffener 224 is made by thermal or electrical conductivematerial, it can function as heat sink or electromagnetic interferenceshielding layer. The stiffener 224 may also be removed at any time afterthe conformable material 106 is cured.

Referring now to FIG. 3 is the integrated circuit package system 100 ofFIG. 2 in a post lead providing phase of manufacture. The integratedcircuit package system 100 is shown having the integrated circuit 102and the leads 104 mounted atop a provisional chip carrier 302.

The provisional chip carrier 302 can be a dummy silicon wafer, metalfoil, tape or any known form of temporary chip carrier. The provisionalchip carrier 302 may be set on a convey belt 304.

The convey belt 304 can transport the integrated circuit package system100 to various phases of manufacture.

Referring now to FIG. 4 is the integrated circuit package system 100 ofFIG. 2 in a wire-bonding phase of manufacture. The integrated circuitpackage system 100 is shown having the active side 204 of the integratedcircuit 102 connected to the leads 104 with the interconnects 210.

Referring now to FIG. 5 is the integrated circuit package system 100 ofFIG. 2 in a drop conformable material-attaching phase of manufacture.The integrated circuit package system 100 is shown having theconformable material 106 with the buffer layer 220, the adhesive layer222, and the stiffener 224 all attached above the conformable material106 and being pressed over the integrated circuit 102 and the leads 104.

Referring now to FIG. 6 is the integrated circuit package system 100 ofFIG. 2 in a curing phase of manufacture. The integrated circuit packagesystem 100 is shown having the conformable material 106 being cured byradiation 602 such as infrared or ultra violet radiation.

Referring now to FIG. 7 is the integrated circuit package system 100 ofFIG. 2 in a post singulation phase of manufacture. The integratedcircuit package system 100 is shown having the conformable material 106cured, singulated and only partially encapsulating the half-etchedportion 212 of the leads 104.

Since an attaching and curing phase can replace a conventional moldingprocess, the manufacturing cost can be reduced in terms of simplerprocess and reduced process steps. As a result, less equipmentinvestment and cost reduction can be achieved.

Since no mold compound is used, there is no chemical or mechanicaldeflash process for mold flash removal from external I/Os, especiallyfor multi-row configuration that encountered mold flash on lead duringmanufacturing.

Since the manufacturing process has been simplified, an in-line assemblysystem can be used to improve productivity, shorten cycle time, andminimize the human error factor.

Referring now to FIG. 8, therein is shown a cross-sectional view alongline 8-8 of FIG. 1. The integrated circuit package system 100 is shownhaving the lead 104 with two lengthwise sides 802 the upper surface 208and the bottom 216. The two lengthwise sides 802 have the half-etchedportion 212 near the bottom 216.

The conformable material 106 only partially encapsulates the lead 104 onthe upper surface 208 and part of the half-etched portion 212 leavingthe bottom 216 of the lead 104 exposed from the conformable material 106

Referring now to FIG. 9, therein is shown a cross-sectional view of anintegrated circuit package system 900 in a second embodiment of thepresent invention. The integrated circuit package system 900 is shownhaving an integrated circuit 902 such as a wire-bonded die with anactive side 904.

On the periphery of the integrated circuit 902, are leads 906 having anupper surface 908. The upper surface 908 of the leads 906 are connectedto the active side 904 of the integrated circuit 902 with interconnects910 such as bond wires.

The leads 906 are shown having a half-etched portion 912 below the uppersurface 908 of the leads 906. The leads 906 are further shown exposedalong a side 914 and a bottom 916. The leads 906 may be pre-plated withNi, Pt, Au or any combination of them. The leads 906 also can bearranged in single or multiple row formats to match multiple levels ofstacked die.

Encapsulating the interconnects 910 and partially encapsulating theintegrated circuit 902 and the leads 906, is a conformable material 918.The conformable material 918 has a low viscosity and, as temperatureincreases, the viscosity gets lower.

Therefore, the conformable material 918 can be easily pressed over theinterconnects 910, above, and around the integrated circuit 902 and theleads 906, and then cured to harden the conformable material 918.

The leads 906 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 918. The conformable material 918 is shownencapsulating the half-etched portion 912 of the leads 906 to a pointco-planar with the bottom 916 of the leads 906.

It has been discovered that the conformable material 918 should be athermally conductive dielectric material. The conformable material 918can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 918 should be about 100° C. while encapsulatingthe integrated circuit 902 before curing. The viscosity of theconformable material 918 may be in a range of 10 Pa to 2000 Pa. It hasstill further been discovered that the elastic modulus of theconformable material 918 before curing (B-stage) should be less than 300MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 918, a bufferlayer 920 is mounted.

The buffer layer 920 is used to compensate for the coefficient ofthermal expansion mismatch between the conformable material 918 and anadhesive layer 922 attached above the buffer layer 920. It is preferablethat the buffer layer 920 is made of an insulation material.

The adhesive layer 922 may be applied to secure a stiffener 924 abovethe buffer layer 920. The buffer layer 920, the adhesive layer 922, andthe stiffener 924 are preferably thermally conductive to shed excessheat generated by the operation of the integrated circuit 902.

The stiffener 924 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 918 in its uncured or viscous state. When the stiffener 924 ismade by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

Referring now to FIG. 10, therein is shown a cross-sectional view of anintegrated circuit package system 1000 in a third embodiment of thepresent invention. The integrated circuit package system 1000 is shownhaving an integrated circuit 1002 such as a wire-bonded die.

The integrated circuit 1002 is mounted over a die pad 1003. Theintegrated circuit 1002 has an active side 1004. The integrated circuit1002 is attached to the die pad 1003 with a die attach adhesive 1005.

On the periphery of the integrated circuit 1002, are leads 1006 havingan upper surface 1008. The upper surface 1008 of the leads 1006 areconnected to the active side 1004 of the integrated circuit 1002 withinterconnects 1010 such as bond wires.

The leads 1006 are shown having a half-etched portion 1012 below theupper surface 1008 of the leads 1006. The die pad 1003 is also shownhaving the half-etched portion 1012 below an upper surface 1013 of thedie pad 1003.

The leads 1006 are further shown exposed along a side 1014, a bottom1016, and along part of the half-etched portion 1012. The leads 1006 maybe pre-plated with Ni, Pt, Au or any combination of them. The leads 1006also can be arranged in single or multiple row formats to match multiplelevels of stacked die.

Encapsulating the interconnects 1010 and the integrated circuit 1002 andpartially encapsulating the leads 1006, is a conformable material 1018.The conformable material 1018 has a low viscosity and, as temperatureincreases, the viscosity gets lower.

Therefore, the conformable material 1018 can be easily pressed over theinterconnects 1010, above, and around the integrated circuit 1002 andthe leads 1006, and then cured to harden the conformable material 1018.

The leads 1006 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1018. The conformable material 1018 is shownonly partially encapsulating the half-etched portion 1012 of the leads1006.

The conformable material 1018 is also shown only partially encapsulatingthe half-etched portion 1012 of the die pad 1003.

It has been discovered that the conformable material 1018 should be athermally conductive dielectric material. The conformable material 1018can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1018 should be about 100° C. whileencapsulating the integrated circuit 1002 before curing. The viscosityof the conformable material 1018 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1018 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 1018, astiffener 1024 is mounted.

The stiffener 1024 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 1018 in its uncured or viscous state. When the stiffener 1024is made by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

Referring now to FIG. 11, therein is shown a cross-sectional view of anintegrated circuit package system 1100 in a fourth embodiment of thepresent invention. The integrated circuit package system 1100 is shownhaving an integrated circuit 1102 such as a wire-bonded die.

The integrated circuit 1102 is mounted over a die pad 1103. Theintegrated circuit 1102 has an active side 1104. The integrated circuit1102 is attached to the die pad 1103 with a die attach adhesive 1105.

On the periphery of the integrated circuit 1102, are leads 1106 havingan upper surface 1108. The upper surface 1108 of the leads 1106 areconnected to the active side 1104 of the integrated circuit 1102 withinterconnects 1110 such as bond wires.

The leads 1106 are shown having a half-etched portion 1112 below theupper surface 1108 of the leads 1106. The die pad 1103 is also shownhaving the half-etched portion 1112 below an upper surface 1113 of thedie pad 1103.

The leads 1106 are further shown exposed along a side 1114, a bottom1116, and along part of the half-etched portion 1112. The leads 1106 maybe pre-plated with Ni, Pt, Au or any combination of them. The leads 1106also can be arranged in single or multiple row formats to match multiplelevels of stacked die.

Encapsulating the interconnects 1110 and the integrated circuit 1102 andpartially encapsulating the leads 1106, is a conformable material 1118.The conformable material 1118 has a low viscosity and, as temperatureincreases, the viscosity gets lower.

Therefore, the conformable material 1118 can be easily pressed over theinterconnects 1110, above, and around the integrated circuit 1102 andthe leads 1106, and then cured to harden the conformable material 1118.

The leads 1106 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1118. The conformable material 1118 is shownonly partially encapsulating the half-etched portion 1112 of the leads1106.

The conformable material 1118 is also shown only partially encapsulatingthe half-etched portion 1112 of the die pad 1103.

It has been discovered that the conformable material 1118 should be athermally conductive dielectric material. The conformable material 1118can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1118 should be about 100° C. whileencapsulating the integrated circuit 1102 before curing. The viscosityof the conformable material 1118 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1118 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the integrated circuit 1102, a stiffener1124 is mounted.

The stiffener 1124 has a protrusion 1126, which contacts the active side1104 of the integrated circuit 1102. The stiffener 1124 may be made oforganic, metal, ceramic or other material, which is stiff enough to actas a support for the conformable material 1118 in its uncured or viscousstate. The protrusion 1126 of the stiffener 1124 functions as a heatsink drawing heat away from the integrated circuit and dissipating theheat over a large surface area.

Referring now to FIG. 12, therein is shown a cross-sectional view of anintegrated circuit package system 1200 in a fifth embodiment of thepresent invention. The integrated circuit package system 1200 is shownhaving integrated circuits 1202 such as dual wire-bonded dies.

The integrated circuits 1202 are mounted over multiple die pads 1203.The integrated circuits 1202 have active sides 1204. The integratedcircuits 1202 are attached to the multiple die pads 1203 with a dieattach adhesive 1205.

On the periphery of the integrated circuits 1202, are leads 1206 havingan upper surface 1208. The upper surface 1208 of the leads 1206 areconnected to the active sides 1204 of the integrated circuits 1202 withinterconnects 1210 such as bond wires. The active sides 1204 of theintegrated circuits 1202 may also be connected to the multiple die pads1203 with the interconnects 1210.

The leads 1206 are shown having a half-etched portion 1212 below theupper surface 1208 of the leads 1206. The multiple die pads 1203 arealso shown having the half-etched portion 1212 below an upper surface1213 of the multiple die pads 1203.

The leads 1206 are further shown exposed along a side 1214, a bottom1216, and along part of the half-etched portion 1212. The leads 1206 maybe pre-plated with Ni, Pt, Au or any combination of them. The leads 1206also can be arranged in single or multiple row formats to match multiplelevels of stacked die.

Encapsulating the interconnects 1210 and the integrated circuits 1202and partially encapsulating the leads 1206, is a conformable material1218. The conformable material 1218 has a low viscosity and, astemperature increases, the viscosity gets lower.

Therefore, the conformable material 1218 can be easily pressed over theinterconnects 1210, above, and around the integrated circuits 1202 andthe leads 1206, and then cured to harden the conformable material 1218.

The leads 1206 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1218. The conformable material 1218 is shownonly partially encapsulating the half-etched portion 1212 of the leads1206.

The conformable material 1218 is also shown only partially encapsulatingthe half-etched portion 1212 of the multiple die pads 1203.

It has been discovered that the conformable material 1218 should be athermally conductive dielectric material. The conformable material 1218can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1218 should be about 100° C. whileencapsulating the integrated circuit 1202 before curing. The viscosityof the conformable material 1218 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1218 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 1218, astiffener 1224 is mounted.

The stiffener 1224 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 1218 in its uncured or viscous state. When the stiffener 1224is made by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

Referring now to FIG. 13, therein is shown a cross-sectional view of anintegrated circuit package system 1300 in a sixth embodiment of thepresent invention. The integrated circuit package system 1300 is shownhaving an integrated circuit 1302 such as a flip-chip with an activeside 1304.

On the periphery and below the integrated circuit 1302, are leads 1306having an upper surface 1308. The upper surface 1308 of the leads 1306are connected to the active side 1304 of the integrated circuit 1302with interconnects 1310 such as solder balls.

The leads 1306 are shown having a half-etched portion 1312 below theupper surface 1308 of the leads 1306. The leads 1306 are further shownexposed along a side 1314, a bottom 1316, and along part of thehalf-etched portion 1312. The leads 1306 may be pre-plated with Ni, Pt,Au or any combination of them. The leads 1306 also can be arranged insingle or multiple row formats to match multiple levels of stacked die.

Encapsulating the interconnects 1310 and the integrated circuit 1302 andpartially encapsulating the leads 1306, is a conformable material 1318.The conformable material 1318 has a low viscosity and, as temperatureincreases, the viscosity gets lower.

Therefore, the conformable material 1318 can be easily pressed over theinterconnects 1310, above, and around the integrated circuit 1302 andthe leads 1306, and then cured to harden the conformable material 1318.

The leads 1306 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1318. The conformable material 1318 is shownonly partially encapsulating the half-etched portion 1312 of the leads1306.

It has been discovered that the conformable material 1318 should be athermally conductive dielectric material. The conformable material 1318can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1318 should be about 100° C. whileencapsulating the integrated circuit 1302 before curing. The viscosityof the conformable material 1318 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1318 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. An adhesive layer 1322 above the conformablematerial 1318 may be applied to secure a stiffener 1324 to theconformable material 1318.

The stiffener 1324 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 1318 in its uncured or viscous state. When the stiffener 1324is made by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

Referring now to FIG. 14, therein is shown a cross-sectional view of anintegrated circuit package system 1400 in a seventh embodiment of thepresent invention. The integrated circuit package system 1400 is shownhaving an integrated circuit 1402 such as a wire-bonded die with anactive side 1404.

On the periphery of the integrated circuit 1402, are leads 1406 havingan upper surface 1408. The upper surface 1408 of the leads 1406 areconnected to the active side 1404 of the integrated circuit 1402 withinterconnects 1410 such as bond wires.

The leads 1406 are shown having a half-etched portion 1412 below theupper surface 1408 of the leads 1406. The leads 1406 are further shownexposed along a side 1414, a bottom 1416, and along part of thehalf-etched portion 1412. The leads 1406 may be pre-plated with Ni, Pt,Au or any combination of them. The leads 1406 also can be arranged insingle or multiple row formats to match multiple levels of stacked die.

Encapsulating the interconnects 1410 and partially encapsulating theintegrated circuit 1402 and the leads 1406, is a conformable material1418. The conformable material 1418 has a low viscosity and, astemperature increases, the viscosity gets lower.

Therefore, the conformable material 1418 can be easily pressed over theinterconnects 1410, above, and around the integrated circuit 1402 andthe leads 1406, and then cured to harden the conformable material 1418.

The leads 1406 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1418. The conformable material 1418 is shownonly partially encapsulating the half-etched portion 1412 of the leads.

It has been discovered that the conformable material 1418 should be athermally conductive dielectric material. The conformable material 1418can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1418 should be about 100° C. whileencapsulating the integrated circuit 1402 before curing. The viscosityof the conformable material 1418 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1418 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 1418, astiffener 1424 is mounted.

The stiffener 1424 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 1418 in its uncured or viscous state. When the stiffener 1424is made by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

The stiffener 1424 is connected to the leads 1406 with a conductiveinterconnection 1426. The conductive interconnection 1426 enhances theability of the stiffener 1424 to act as an electromagnetic interferenceshielding by funneling current resulting from ionizing radiation to agrounding pin.

Referring now to FIG. 15, therein is shown a cross-sectional view of anintegrated circuit package system 1500 in an eighth embodiment of thepresent invention. The integrated circuit package system 1500 is shownhaving an integrated circuit 1502 such as a wire-bonded die with anactive side 1504.

On the periphery of the integrated circuit 1502, are leads 1506 havingan upper surface 1508. The upper surface 1508 of the leads 1506 areconnected to the active side 1504 of the integrated circuit 1502 withinterconnects 1510 such as bond wires.

The leads 1506 are shown having a half-etched portion 1512 below theupper surface 1508 of the leads 1506. The leads 1506 are further shownexposed along a side 1514, a bottom 1516, and along part of thehalf-etched portion 1512.

To facilitate improved mechanical locking, the leads 1506 have thehalf-etched portion 1512 along the side 1514 and the bottom 1516 of theleads 1506. The leads 1506 may be pre-plated with Ni, Pt, Au or anycombination of them. The leads 1506 also can be arranged in single ormultiple row formats to match multiple levels of stacked die.

Encapsulating the interconnects 1510 and partially encapsulating theintegrated circuit 1502 and the leads 1506, is a conformable material1518. The conformable material 1518 has a low viscosity and, astemperature increases, the viscosity gets lower.

Therefore, the conformable material 1518 can be easily pressed over theinterconnects 1510, above, and around the integrated circuit 1502 andthe leads 1506, and then cured to harden the conformable material 1518.

The leads 1506 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1518. The conformable material 1518 is shownonly partially encapsulating the half-etched portion 1512 of the leads.

It has been discovered that the conformable material 1518 should be athermally conductive dielectric material. The conformable material 1518can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1518 should be about 100° C. whileencapsulating the integrated circuit 1502 before curing. The viscosityof the conformable material 1518 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1518 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 1518, astiffener 1524 is mounted.

The stiffener 1524 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 1518 in its uncured or viscous state. When the stiffener 1524is made by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

Referring now to FIG. 16, therein is shown a cross-sectional view of anintegrated circuit package system 1600 in a ninth embodiment of thepresent invention. The integrated circuit package system 1600 is shownhaving an integrated circuit 1602 such as a wire-bonded die with anactive side 1604.

On the periphery of the integrated circuit 1602, are leads 1606 havingan upper surface 1608. The upper surface 1608 of the leads 1606 areconnected to the active side 1604 of the integrated circuit 1602 withinterconnects 1610 such as bond wires.

The leads 1606 are shown having a half-etched portion 1612 below theupper surface 1608 of the leads 1606. The leads 1606 are further shownexposed along a side 1614, a bottom 1616, and along part of thehalf-etched portion 1612.

To facilitate easier singulation, the leads 1606 have the half-etchedportion 1612 along the side 1614 and the upper surface 1608 of the leads1606. The leads 1606 may be pre-plated with Ni, Pt, Au or anycombination of them. The leads 1606 also can be arranged in single ormultiple row formats to match multiple levels of stacked die.

Encapsulating the interconnects 1610 and partially encapsulating theintegrated circuit 1602 and the leads 1606, is a conformable material1618. The conformable material 1618 has a low viscosity and, astemperature increases, the viscosity gets lower.

Therefore, the conformable material 1618 can be easily pressed over theinterconnects 1610, above, and around the integrated circuit 1602 andthe leads 1606, and then cured to harden the conformable material 1618.

The leads 1606 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1618. The conformable material 1618 is shownonly partially encapsulating the half-etched portion 1612 of the leads.

It has been discovered that the conformable material 1618 should be athermally conductive dielectric material. The conformable material 1618can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1618 should be about 100° C. whileencapsulating the integrated circuit 1602 before curing. The viscosityof the conformable material 1618 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1618 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 1618, anadhesive layer 1622 attaches a stiffener 1624 to the conformablematerial 1618.

The stiffener 1624 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 1618 in its uncured or viscous state. When the stiffener 1624is made by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

Referring now to FIG. 17, therein is shown a cross-sectional view of anintegrated circuit package system 1700 in a tenth embodiment of thepresent invention. The integrated circuit package system 1700 is shownhaving an integrated circuit 1702 such as a wire-bonded die with anactive side 1704.

On the periphery of the integrated circuit 1702, are leads 1706 havingan upper surface 1708. The upper surface 1708 of the leads 1706 areconnected to the active side 1704 of the integrated circuit 1702 withinterconnects 1710 such as bond wires. The leads 1706 are shown having ahalf-etched portion 1712 along sides 1714 of the leads 1706.

To facilitate connection to a printed circuit board the leads haveexternal interconnects 1717 such as solder balls attached to a bottom1716 of the leads 1706. The leads 1706 may be pre-plated with Ni, Pt, Auor any combination of them. The leads 1706 also can be arranged insingle or multiple row formats to match multiple levels of stacked die.

Encapsulating the interconnects 1710 and partially encapsulating theintegrated circuit 1702 and the leads 1706, is a conformable material1718. The conformable material 1718 has a low viscosity and, astemperature increases, the viscosity gets lower.

Therefore, the conformable material 1718 can be easily pressed over theinterconnects 1710, above, and around the integrated circuit 1702 andthe leads 1706, and then cured to harden the conformable material 1718.

The leads 1706 can be any shape and cross-section, such as T shape,trapezoid, L shape, etc, that enhances mechanical locking effect withthe conformable material 1718. The conformable material 1718 is shownonly partially encapsulating the half-etched portion 1712 of the leads.

It has been discovered that the conformable material 1718 should be athermally conductive dielectric material. The conformable material 1718can be made of a B-stage material that can be hardened after curing andcan maintain a predetermined thickness.

The conformable material 1718 should be about 100° C. whileencapsulating the integrated circuit 1702 before curing. The viscosityof the conformable material 1718 may be in a range of 10 Pa to 2000 Pa.It has still further been discovered that the elastic modulus of theconformable material 1718 before curing (B-stage) should be less than300 MPa, and it should be greater than 3000 MPa after curing.

There should preferably be a difference about 10× before and aftercuring. The elastic modulus should also drop as temperature increasesbefore and after curing. Above the conformable material 1718, astiffener 1724 is mounted.

The stiffener 1724 may be made of organic, metal, ceramic or othermaterial, which is stiff enough to act as a support for the conformablematerial 1718 in its uncured or viscous state. When the stiffener 1724is made by thermal or electrical conductive material, it can function asheat sink or electromagnetic interference shielding layer.

Referring now to FIG. 18, therein is shown a flow chart of a system 1800for manufacturing the integrated circuit package system 100 of FIG. 1 inan embodiment of the present invention. The system 1800 includesproviding an integrated circuit in a block 1802; mounting a lead on theperiphery of the integrated circuit in a block 1804; connecting theintegrated circuit to the lead with an interconnect in a block 1806; andforming a conformable material by pressing the conformable material onthe integrated circuit, the lead, and the interconnect in a block 1808.

It has been discovered that the present invention thus has numerousaspects. As conventional molding process is replaced by isolative layerattaching and curing, manufacturing cost can be reduced in terms ofshorter cycle time, less equipment investment, and simpler process.

Another aspect is as leads are partially embedded in an isolative layer,more wetting area is exposed during board level attachment and boardlevel reliability can be improved.

Yet another aspect is lead-to-lead silver migration can be prevented.

Finally, another aspect is as no mold compound is used, there is nochemical or mechanical deflash process for mold flash removal fromexternal I/Os, especially for multi-row configuration that encounteredmold flash on lead during manufacturing.

These and other valuable aspects of the present invention consequentlyfurther the state of the technology to at least the next level.

Thus, it has been discovered that the conformable material system of thepresent invention furnishes important and heretofore unknown andunavailable solutions, capabilities, and functional aspects forintegrated circuit package systems. The resulting processes andconfigurations are straightforward, cost-effective, uncomplicated,highly versatile, accurate, sensitive, and effective, and can beimplemented by adapting known components for ready, efficient, andeconomical manufacturing, application, and utilization.

While the invention has been described in conjunction with a specificbest mode, it is to be understood that many alternatives, modifications,and variations will be apparent to those skilled in the art in light ofthe aforegoing description. Accordingly, it is intended to embrace allsuch alternatives, modifications, and variations that fall within thescope of the included claims. All matters hithertofore set forth hereinor shown in the accompanying drawings are to be interpreted in anillustrative and non-limiting sense.

1. An integrated circuit package system comprising: providing anintegrated circuit; mounting a lead on the periphery of the integratedcircuit; connecting the integrated circuit to the lead with aninterconnect; and forming a conformable material by pressing theconformable material on the integrated circuit, the lead, and theinterconnect.
 2. The system as claimed in claim 1 further comprising:attaching a stiffener to the conformable material.
 3. The system asclaimed in claim 1 further comprising: attaching a stiffener to theconformable material with an adhesive layer.
 4. The system as claimed inclaim 1 further comprising: attaching a stiffener to a buffer layer withan adhesive layer; and attaching the buffer layer to the conformablematerial.
 5. The system as claimed in claim 1 further comprising:attaching a stiffener having a protrusion to the conformable materialand having the protrusion in contact with the integrated circuit.
 6. Anintegrated circuit package system comprising: providing an integratedcircuit; mounting a lead having a half-etched portion on the peripheryof the integrated circuit; connecting the integrated circuit to the leadwith a bond wire, a solder ball, or a combination thereof; and forming aconformable material by pressing the conformable material on theintegrated circuit, and the lead.
 7. The system as claimed in claim 6further comprising: mounting the integrated circuit to a die pad havinga half-etched portion.
 8. The system as claimed in claim 6 wherein:mounting a lead includes forming the half-etched portion along a sideand bottom of the lead, along a side and upper surface of the lead, or acombination thereof.
 9. The system as claimed in claim 6 furthercomprising: mounting an external interconnect to the lead.
 10. Thesystem as claimed in claim 6 further comprising: connecting the lead tothe stiffener with a conductive interconnection.
 11. An integratedcircuit package system comprising: an integrated circuit; a lead mountedon the periphery of the integrated circuit; an interconnect connectingthe integrated circuit to the lead; and a conformable material pressedon the integrated circuit, the lead, and the interconnect.
 12. Thesystem as claimed in claim 11 further comprising: a stiffener attachedto the conformable material.
 13. The system as claimed in claim 11further comprising: a stiffener attached to the conformable materialwith an adhesive layer.
 14. The system as claimed in claim 11 furthercomprising: a stiffener attached to a buffer layer with an adhesivelayer; and wherein: the buffer layer is attached to the conformablematerial.
 15. The system as claimed in claim 11 further comprising: astiffener having a protrusion attached to the conformable material andhaving the protrusion in contact with the integrated circuit.
 16. Thesystem as claimed in claim 11 wherein: the lead has a half-etchedportion; and the interconnect connecting the integrated circuit to thelead is a bond wire, a solder ball, or a combination thereof.
 17. Thesystem as claimed in claim 16 further comprising: a die pad having ahalf-etched portion mounted to the integrated circuit.
 18. The system asclaimed in claim 16 wherein: the half-etched portion is formed along aside and bottom of the lead, along a side and upper surface of the lead,or a combination thereof.
 19. The system as claimed in claim 16 furthercomprising: an external interconnect mounted to the lead.
 20. The systemas claimed in claim 16 further comprising: a conductive interconnectionconnecting the lead to the stiffener.